Structures and Properties of Oxygen-Substituted Li10SiP2S12–xOx Solid-State Electrolytes

Abstract

Li10SiP2S12 (LSiPS), which has an Li10GeP2S12 (LGPS)-type crystalline structure, was synthesized by solid-state reaction and then doped with oxygen to produce oxy-sulfide compositions of the general formula Li10SiP2S12–xOx (LSiPSO), where 0 ≤ x ≤ 1.75. The phase distribution and local structural units present in the LSiPSO materials were determined via a combination of powder X-ray diffraction and Raman, Fourier-transform infrared, and solid-state nuclear magnetic resonance (NMR) spectroscopies. At smaller amounts of O substitution for S, x < 1, in LSiPS, the structure of the LSiPSO phases became more uniform in the LGPS structure from smaller amounts of the impurity β-Li3PS4 and more of the oxygen-substituted LGPS-like structure. Consistent with this, the Li ion conductivity increases in proportion to the decrease in the amount of the β-Li3PS4 phase and the growth of the LGPS-like phase. The highest lithium ionic conductivity was found for x = 0.7 at 3.1 (±0.4) × 10–3 S/cm at 25 °C. However, for x ≥ 0.9,...